Electro-magnetic signal responsive device



July 21, 1964 R. SJBARTEL ETAL ELECTRO-MAGNETIC SIGNAL RESPONSIVE DEVICEFiled Sept. 14. 1959 FIG. 2b

v INVENTORS Rom 's.- BARTEL, 1 By DAVID w.- BRIGHT M 4/4 United StatesPatent Oflice York Filed Sept. 14, 1959, Ser. No. 839,906 2 Claims. (Cl.340174) This invention relates to devices which employ an input signalto warp a magnetic field for the production of an output signal, andmore particularly to novel means employing that principle for theproduction of an output signal which is a desired function of a numberof input signals.

It is a very desirable feature of computer technology to be able toemploy signal translating means which are reliable, easy and inexpensiveto manufacture, sufficiently rugged to withstand wide temperaturechanges and rough handling, and can operate at very high speeds. Amongthe signal relationships the detection of which is often required arethe presence of a signal on one of several lines or the simultaneousexistence of certain signals on a plurality of lines, with theadditional requirement that direct connection between the lines underinvestigation is to be avoided.

The present invention attains the foregoing and other capabilities byemploying a plurality of insulated wires, one for each of the severalcircuits to which the device is to be responsive, around which there isdisposed a metallic wrapping, such metallic wrapping being comprised ofan iron-nickel composition having a substantially squareloop hysteresischaracteristic. The wrapping may be fabricated by being wound onto thewire containing base structure or may be in the form of an iron-nickelfilm that is electroplated or otherwise deposited in place about thebase structure, such deposited iron-nickel film having a substantiallysquare-hysteresis loop characteristic.

Initially, a magnetic field of suificient intensity is applied to themetallic wrap for the purpose of storing a magnetic field within thewrap, such magnetic field being in a longitudinal direction with respectto the wrap as well as the base wires. An output winding is provided,wound about the outside of the wrap, where it is in position to sensechanges in the field of the wrap when that field is warped by the neteffect of input current signals carried by the wires, the currentsignals tending to set up fields in planes transverse to the axis of thewrap and the field thereof. Upon termination of the input pulses, themagnetic field of the wrap returns to its undisturbed state, withaccompanying production of an output pulse of a sign opposite to thatproduced by the initiation of the input. The signs of the output pulsesare dependent on the polarity of the wrap, not on the sign of thealgebraic sum of the input pulses; therefore devices of the inventionhave added utility where input pulse initiation and termination are ofseparate interest, or where the output can be utilized only in a certainpolarity. Should it be desired to reverse the output polaritycharacteristic of the device, this can be done by reversing the residualfield of the wrap, as by passing a current through the windingtherearound or providing another, similarly disposed winding for thatpurpose, or by otherwise exposing the wrap to a reversing or switchingfield.

For bucking return of flux of the wrap through the center thereof andthereby forcing more of that fiux to follow paths linking the outputwinding so as to increase the sensitivity of the device, it is preferredthat the base itself contain magnetic material which adopts the' samepolarity as the wrap when the wrap is magnetized. This material could beembodied in the input wires them- 3,142,046 Patented July 21, 1964selves by using magnetic material for these wires, but it is preferredthat this material be in the form of a separate filament or rod disposedalong the axis of the wrap.

It is an object of the invention to provide an improved multiple inputsignal responsive device.

It is another object of the invention to provide such response byemployment of quadrature fields;

It is still another object of the invention to provide an improveddevice as aforesaid which is operative to yield an output which is of aquantity corresponding to the algebraic sum of coincident input signals,

It is another object of the invention to provide said sum in apredeterminable polarity.

It is yet another object of the invention to provide a device asaforesaid which is inexpensive to manufacture, is small in size, and canproduce moderately high output voltages. i i I 7 Other objects of theinvention will be apparent from the foregoing and from the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of example, the principle of the invention andthe best mode, which has been contemplated, of applying that principle.I

FIG. 1 is a representation, partly schematic,,of a signal responsivedevice in accordance with the invention;

FIGS. 2a and 2b are, respectively, representations of input pulses whichmay be employed and output pulses obtained, in the practice of theinvention; and

FIG. 3 is a square-loop hysteresis curve representing the B-Hcharacteristic of the magnetic material forming the wrap or shell of thedevice of FIG. 1.

Turning to FIG. 1, there are shown a plurality of wires 5, 6, 7, 8 ofsuitable non-magnetic, conductive material such as copper, insulated, asindicated, and disposed adjacent to a rod 9 of magnetic material. Placedabout the assembly thus far described is a permalloy wrap 10 composed ofa nickel-iron alloy material that has a square loop hysteresischaracteristic. A winding 11 is wound about the wrap 10 to serveprimarily as the output winding of the device, but may be employed alsowhen desired to magnetize initially, or to reverse the residualmagnetization of, the wrap, or another winding, similar to the winding11 shown, or other means could be employed for this purpose. Thus itwill be understood that the wrap 10 has, as employed, a magnetic fieldin and about the wrap, oriented longitudinally of the generallycylindrical wrap and linking the winding 11, and that input currentpassing through any of the wires 5, 6, 7, 8 within the wrap will tend toset up fields transverse to those wires and in quadrature to thefield'of the wrap.

Operation of the device of FIG. 1 can be better understood by referringto FIGS. 2 and 3 in conjunction with FIG. 1. Assume that the wrap 10 hasbeen magnetized from any source of such a polarity as to create a fluxfield that leaves the :wrap from one of its ends and returns to the wrapat its other end, leaving the wrap with a residual field of thatconfiguration. A current pulse 12, having a positive polarity, isapplied to wire 5 so as to create a momentary field that is at rightangles to the steady magnetic field associated with the wrap 10. Themomentary field, being perpendicular to the residual field of the wrap,warps the residual field so that there is a'change d w (-fi=change offlux with respect to time) wrap to snap back to its remanent condition,such return to its remanent condition causing another output voltagepulse 16, opposite in sign to the first output pulse 15, to appearacross the terminals 13, 14. Conventional means may be employed in theoutput circuit, not shown, connected to terminals 13, 14 that willdiscriminate between voltage outputs 15 and 16, so as to utilize onlyone of the pulses or both, as desired.

If the residual field of the wrap 10 were reversed, the signs of theoutput pulses 15, 16 would be reversed, but reversal of the sign of thenet input to the lines 5, 6, 7, 8 has no effect on the signs of theoutput. Thus, if a negative pulse 17 is passed through one of the inputlines 5, 6, 7, 8, the resulting output pulses 18, 19 will be of the samesign sequence as the first described output pulses 15, 16, although,since the illustrated negative input pulse is of reduced amplitude, theoutput pulses will be of correspondingly smaller size. In each case, theinput pulse has operated merely to diminish momentarily the number oflines of flux of a steady polarity which cut the output winding 11,which steady polarity can be reversed only by reversal of the residualmagnetization of the wrap 10.

Thus, the device is insensitive to the polarity of a given input pulsebut it is responsive to the net change in flux which cuts the winding11, with respect to time, resulting from the net current passing throughthe wrap 10. Accordingly, the device is capable of adding algebraicallysimultaneous signals on the input lines and yielding an output which hasan amplitude corresponding to the algebraic sum of the amplitudes of thesimultaneous input signals, so that if, for example, the pulsesillustrated at 12, 17, 20, 21 in FIG. 2a, having an algebraic sum ofzero, were fed simultaneously through the respective input lines 5, 6,7, 8, the output induced in the winding 11 would be substantially zero,the currents through the input lines 5, 6, 7, 8 being self cancelling intheir effect on the field of the wrap 10.

As follows from the foregoing, the present storage device operates withquadrature fields wherein the magnetic wrap 10 behaves as a permanentmagnet in the longitudinal direction and as a magnetic core Withoutremanence in the transverse direction. The wrap 10 is a cylinder whoselongitudinal axis is considerably longer than its effective diameter, orthe wrap is dimensionally anisotropic. The poles are at either end ofthe wrap 10 and the lines of flux leave one end of the wrap, travelthrough air, and return to the wrap at the other end.

FIG. 3 is a showing of the hysteresis loop of Wrap 10 in thelongitudinal direction. In general, the maximum amount of potentialenergy stored during static conditions of the magnetized wrap isproportional to its shape anisotropy, or the ratio of its longitudinalaxis to its cross-sectional diameter. The wrap 10 is not at residual orremanent point C, but is under the influence of a demagnetizing fieldthat exists because of shape anisotropy of the wrap and rests at point Aduring static conditions, for a given residual polarity. When an inputcurrent pulse 12 is applied to one of the lines 5, 6, 7, 8 it creates atransver'seflux field that causes the flux of the Wrap that travelsthrough the air and links the output winding 11 to decrease frorn A toalong line 22. This reduction of flux in the longitudinal direction ofwrap is represented by the load or shear-line 22. The curve, e.g., loadand shear-line 22, for a permanent magnet that is of importance to anunderstanding of the invention lies between the positive residualinduction point C and the coercive force Hc, or between negativeresidual induction point D and +Hc. This portion of the curve, alsocalled the demagnetization curve, will determine the magnetic energyavailable when the permanent field is changed in going from A to O, orin going from B to 0.

When the input pulse 12 is applied to one of the input wires 5, 6, 7, 8,the transverse field causes the flux in the air between the ends of wrap10 to diminish from A to O, and the flux energy available cuts theoutput winding 11 to produce theoutput 15, the terminating of the inputpulse 12 and the attendant collapse of the transverse field causing thepermanent field to go back from O to A along line 22 to produce outputvoltage pulse 16. The voltage signal outputs 15, 16 or 18, 19 are afunction of the rise time and amplitude of the input pulse 12 or 17applied, the number of turns in the output winding 11, and the directionand amount of magnetization of the wrap in the longitudinal direction.

The magnetic material rod 9 provides an opposing field due to itsmagnetization in the same direction as the magnetic field of the wrap,thereby causing more lines of flux to encompass the output winding 11instead of returning through the interior of the cylindrical wrap. Thisdiversion of the magnetic field arises because the polarity of one endof the field of wrap is the same as the polarity of the field on rod 9that is adjacent such end. The same polarity fields thus repel eachother. It has been found that this provides a greater amount of flux,resulting in a greater changing of the fiux field with respect to timefrom A to 0, so as to produce higher voltage output signals than wouldbe obtained without the rod 9.

From the foregoing, it will be seen that devices in accordance with theinvention have utility in many different employments in computers andthe like. For example, the device can sense the fact that there is asignal on one line or a signal on another line, but not bothsimultaneously, it being a simple matter to choose the sign which asignal of given polarity will have in the algebraic addition performedby the device by wiring the corresponding circuit through one of theinput lines of the device in the appropriate direction. Also, the devicecan sense diiferences in rise times, pulse widths, and, with suitablediscriminating circuitry connected to the output Winding, show that eachof several signals of varying amplitudes are present simultaneously. Thecurrent pulses to be compared, such as the pulses 12, 17, 20, 21 shownin FIG. 2a, may be supplied to the wires 5, 6, 7, 8 from any suitablesources, as indicated at 23, 24, 25 and 26 in FIG. 1.

The wrap 10 may be wound about the insulated wire and rod base 5, 6, 7,8, 9 until a certain thickness of wrap is attained, or the magneticmaterial that constitutes the wrap may be deposited in place on thatbase by means of suitable electroplating and/ or vacuum-depositingtechniques, or the like. In general, the thinner the Wrap, the fasterthe response of the device. Representative,

though not limiting, the length of the generally cylindrical wrap 10 maybe 4 inch, with its diameter being inch, the wrap 10 consisting of awinding of five superposed turns of /8 mil permalloy. In the foregoingexample, the rod 9 may be A inch long and about inch in diameter, withthe wires 5, 6, 7, 8 being number 40 lacquered copper wire. It will beunderstood that the device may be miniaturized further, and with the useof vacuum deposition techniques, the thickness of the wrap 10 may bemeasured in angstroms, it being understood that the device should becompact crosssectionally, the somewhat expanded view of FIG. 1 being forclarity of illustration.

The above described device is an inexpensive, easily manufactured, andreliable device that is capable of high speed operations. Moreover, bychoosing a wrap 10 material that has a high remanent magentism in thelongitudinal direction, one can attain high voltage output signals withrelatively small input currents. Furthermore the small size capabilityof the device lends itself to employment in large numbers as may berequired in computer usages.

While there has been shown and described and pointed out fundamentalnovel features of the invention as applied to a preferred embodiment, itwill be understood that various omissions and substitutions and changesin the form and details of the device illustrated and in its operationmay be made by those skilled in the art Without departing from thespirit of the invention. It is the intention therefore, to be limitedonly as indicated by the scope of the following claims.

What is claimed is:

1. A current signal adding device comprising a plurality ofelectrically-conducting elements, an axially elongate cylindrical wrapof magnetic material about said elements, said wrap having asubstantially rectangular hysteresis loop characteristic and having aresidual field oriented parallel to its longitudinal axis,simultaneously operative plural input source means connected to sendcurrent pulses through respective ones of said elements so as to createan annular magnetic field in quadrature to said residual field of saidwrap so as to momentarily change said residual magnetic field of saidwrap in accordance with the instantaneous algebraic sum of said pulses,and an output winding about said wrap for sensing the scaler value ofthe momentary changes of said residual field due to the simultaneousalgebraic sum of the annular magnetizing forces during the rise and falltimes of said current pulses.

2. A current signal adding device comprising a plurality ofelectrically-conducting elements, an axially elongate cylindrical wrapof magnetic material about said elements, said wrap having asubstantially rectangular hysteresis loop characteristic and having aresidual field oriented parallel to its longitudinal axis, a rod ofmagnetic material oriented longitudinally within said wrap having aresidual magnetic polarity which is the same as that of said wrap tooppose axial return flux through said Wrap, simultaneously operativeplural input source means connected to send current pulses throughrespective ones of said elements so as to create an annular magneticfield in quadrature to said residual field of said Wrap so as tomomentarily change said residual magnetic field of said wrap inaccordance with the instantaneous algebraic sum of said pulses, and anoutput winding about said wrap for sensing the sealer value of themomentary changes of said residual field due to the simultaneousalgebraic sum of the annular magnetizing forces during the rise and falltimes of said current pulses.

References Cited in the file of this patent UNITED STATES PATENTS Devolet al. Apr. 10, 1956 Lipkin Oct. 29, 1957 Van Allen Oct. 6, 1959

2. A CURRENT SIGNAL ADDING DEVICE COMPRISING A PLURALITY OFELECTRICALLY-CONDUCTING ELEMENTS, AN AXIALLY ELONGATE CYLINDRICAL WRAPOF MAGNETIC MATERIAL ABOUT SAID ELEMENTS, SAID WRAP HAVING ASUBSTANTIALLY RECTANGULAR HYSTERESIS LOOP CHARACTERISTIC AND HAVING ARESIDUAL FIELD ORIENTED PARALLEL TO ITS LONGITUDINAL AXIS, A ROD OFMAGNETIC MATERIAL ORIENTED LONGITUDINALLY WITHIN SAID WRAP HAVING ARESIDUAL MAGNETIC POLARITY WHICH IS THE SAME AS THAT OF SAID WRAP TOOPPOSE AXIAL RETURN FLUX THROUGH SAID WRAP, SIMULTANEOUSLY OPERATIVEPLURAL INPUT SOURCE MEANS CONNECTED TO SEND CURRENT PULSES THROUGHRESPECTIVE ONES OF SAID ELEMENTS SO AS TO CREATE AN ANNULAR MAGNETICFIELD IN QUADRATURE TO SAID RESIDUAL FIELD OF SAID WRAP SO AS TOMOMENTARILY CHANGE SAID RESIDUAL MAGNETIC FIELD OF SAID WRAP INACCORDANCE WITH THE INSTANTANEOUS ALGEBRAIC SUM OF SAID PULSES, AND ANOUTPUT WINDING ABOUT SAID WRAP FOR SENSING THE SCALER VALUE OF THEMOMENTARY CHANGES OF SAID RESIDUAL FIELD DUE TO THE SIMULTANEOUSALGEBRAIC SUM OF THE ANNULAR MAGNETIZING FORCES DURING THE RISE AND FALLTIMES OF SAID CURRENT PULSES.